Kortek Monitors Tips,Tricks and Cap Kits

With no sync signal it would measure different Dc on each pin vs
with a signal to tell if it is getting along the sync path
and that it reacts to a signal.. or not. to tell what is working
Anyway
The Zener needs to be 5.1 goes to pin 14 the vcc pin page 22
i can't see the location number on schematic for the zener.
you might confirm the grounds around the ic is the same
your looking to make sure the grounds for the ic
is common to input ground
You might remove the sync wire from the connector
and go to the base of Q301 if you want.
and see what happen to the sync
Otherwise, i don't have any more ideas for you.
Since you replace the other parts.
 
Help with Kortek KT-1420A…

Monitor Identification

Actually this is a Tekbuilt monitor, but the parts side of the chassis reads KI-2-VO and the solder side reads SAM 900901. I downloaded all 5 manuals for these Korean monitors (Kortek KT-1420A, Imperial, Penn Ray, Tekbuilt & Wico SUM-20C). All of them are very similar, but none of them match up 100% to the components and component numbering. However, the Tekbuilt one seems to be the closest.






Problem

This monitor chassis had a blown DC fuse at F602 before I started working on it. I referenced Ken Layton's Kortek repair guide and Randy Fromm's Tekbuilt flow chart. From what I read if F602 blows, its either the HOT, R612 or the Flyback.

I did everything below and it continues to instantly blow the F602 DC fuse…

Repair Log

Recapped & Reflowed: Replaced all electrolytic capacitors and filter cap, reflowed headers, checked for cold solder joints and broken traces. Through component testing I have probably reflowed 50%+ of this chassis.

Transistors: Replaced HOT Q402, failed testing while removed from circuit. Verified Voltage Regulator Q601 good out of circuit. Q602-604, Q401, Q431, Q201 & Q202 tested good out of circuit.

Resistors: Verified R612 5 ohm 5 watt was good. Replaced R610 15K ohm 1 watt was reading @ 13.6K. Replaced R611 7.5 ohm 3 watt was reading @ 6.43. Verified ohms and reflowed every other 1-5 watt resistor. Checked all other resistors for open condition in circuit.

Diodes & Zener Diodes: All tested good while checking in and out of circuit, depending on reading in circuit.

Bridge Rectifier: Checked good out of circuit.

Pots: R415 5 ohm pot for X-ray circuit tested good out of circuit.

Flyback: Removed and inspected, no signs of burns or arcing.

B+ Voltage: Reading steady 118.7v DC at the input side of the F602.

F602: Resistance to ground on output side of F602 is 19.4 ohms.

Yoke: Horizontal 2.30 ohms & Vertical 2.68 ohms. No shorts. Found chaffed wire on vertical, repaired w/solder and heat shrink tubing.

Any help or suggestions are appreciated!
 
Last edited:
ok , need to get to the Horizontal ic 401
Im looking at a chassis bottom online.

whats the number on the part
get datasheet so we can check the pins
Common to get cold solder joints on the 1,5, watts resistor
along the B+ path. see areas where the resistors make the board dark?

Just need to clean up and confirm good connections to the Vcc 12vs
of Ic 401
Then need to disable the hold down pin.
to force the HV
now if you have HV then turn up the screen
see anything?

Its easier to ID a chassis schematic by the major parts it use's
Not they look alike.
100k 1 watt sound like a odd value 10k sounds better
Need to check for a short to ground on either side of it
or the voltage on each side.
 
Ohmerone said:
ok , need to get to the Horizontal ic 401
Im looking at a chassis bottom online.

whats the number on the part
get datasheet so we can check the pins
Common to get cold solder joints on the 1,5, watts resistor
along the B+ path. see areas where the resistors make the board dark?

Just need to clean up and confirm good connections to the Vcc 12vs
of Ic 401
Then need to disable the hold down pin.
to force the HV
now if you have HV then turn up the screen
see anything?

Its easier to ID a chassis schematic by the major parts it use's
Not they look alike.
100k 1 watt sound like a odd value 10k sounds better
Need to check for a short to ground on either side of it
or the voltage on each side.
Click to expand...
I edited my original post with updated information and to create a repair log to track what I have done.

I followed your suggestions and here is what I came up with...

IC401: HA11235 data sheet attached.

1-5 Watt Resistors: Measured ohms and reflowed all of them. I found that R611 7.5 ohm 3 watt made the board dark and measured at 6.43 ohms, so I replaced it.

R503: The manual does call for a 100K ohm 1 watt and that's what was in it. But I actually made a mistake previously and it tested good out of circuit, so please disregard.

Thank you for your assistance Ohmerone!
 

Attachments

  • HA11235 Datasheet.pdf
    267.7 KB · Views: 7
Jano18 said:
I edited my original post with updated information and to create a repair log to track what I have done.

I followed your suggestions and here is what I came up with...

IC401: HA11235 data sheet attached.

1-5 Watt Resistors: Measured ohms and reflowed all of them. I found that R611 7.5 ohm 3 watt made the board dark and measured at 6.43 ohms, so I replaced it.

R503: The manual does call for a 100K ohm 1 watt and that's what was in it. But I actually made a mistake previously and it tested good out of circuit, so please disregard.

Thank you for your assistance Ohmerone!
Click to expand...
F602: Resistance to ground on output side of F602 is 19.4 ohms.

you want high resistance there like on the other side of the fuse

Just need to follow the 19.4 ohms to ground
keep the chassis off and use your ohm meter only!!

You must clear any low ohms on the B+ starting at the dc fuse
Don't plug in power again until its clear.

I would follow the trace to component's on the trace and lift one end
of the suspect until the 19.4 ohms or lower are found.

You can measure ohms to ground the VCC on the Ic mention
Is it 19.4 ohms if yes then the IC is shorted!
If not you can de-solder the pin and clear it from the trace
while your looking the 19.4 ohms to ground.
 
Ohmerone said:
F602: Resistance to ground on output side of F602 is 19.4 ohms.

you want high resistance there like on the other side of the fuse

Just need to follow the 19.4 ohms to ground
keep the chassis off and use your ohm meter only!!

You must clear any low ohms on the B+ starting at the dc fuse
Don't plug in power again until its clear.

I would follow the trace to component's on the trace and lift one end
of the suspect until the 19.4 ohms or lower are found.

You can measure ohms to ground the VCC on the Ic mention
Is it 19.4 ohms if yes then the IC is shorted!
If not you can de-solder the pin and clear it from the trace
while your looking the 19.4 ohms to ground.
Click to expand...
Checked with my meter, while lifting jumpers and components and traced it all the way back to IC401. I will order one from AP&R and report back if it's solved. Thank you for your assistance!
 
Ohmerone said:
With no sync signal it would measure different Dc on each pin vs
with a signal to tell if it is getting along the sync path
and that it reacts to a signal.. or not. to tell what is working
Anyway
The Zener needs to be 5.1 goes to pin 14 the vcc pin page 22
i can't see the location number on schematic for the zener.
you might confirm the grounds around the ic is the same
your looking to make sure the grounds for the ic
is common to input ground
You might remove the sync wire from the connector
and go to the base of Q301 if you want.
and see what happen to the sync
Otherwise, i don't have any more ideas for you.
Since you replace the other parts.
Click to expand...
Looks like I'm on the right track…I think my batch of extra 74LS86 chips are bad. Kept swapping them around since I socketed the chassis, and eventually got a stable image, but it's not really adjustable and doesn't fit the screen and some walls are messed up…not a board issue though. Ordered some new chips so hopefully have an update this week.
 

Attachments

  • FC0F8F87-7622-45DE-9B2C-F8CCD80CAD99.jpeg
    FC0F8F87-7622-45DE-9B2C-F8CCD80CAD99.jpeg
    2.6 MB · Views: 10
The "messed up walls" looks like your vertical size is just too tall and folding over. Can you shrink the height (and probably move the vertical position down a bit)?

DogP
 
DogP said:
The "messed up walls" looks like your vertical size is just too tall and folding over. Can you shrink the height (and probably move the vertical position down a bit)?

DogP
Click to expand...
Vertical adjustment is acting funky, it's too wide even at the lowest setting, which I believe it was at when I took this picture. Does the same thing on both of my problematic chassis with the same 74LS86 chip. I'm hopeful the chip I have is just bad. I've tested everything else in the circuit except for the ICs because I don't have a comparator. Next thing I'll mess with is the vertical IC201.
 
sk8ersublime said:
Vertical adjustment is acting funky, it's too wide even at the lowest setting, which I believe it was at when I took this picture. Does the same thing on both of my problematic chassis with the same 74LS86 chip. I'm hopeful the chip I have is just bad. I've tested everything else in the circuit except for the ICs because I don't have a comparator. Next thing I'll mess with is the vertical IC201.
Click to expand...
From looking at the schematics, it seems like a weird failure mode for the LS86 to affect vertical size with an otherwise good picture, but I guess anything's possible. Are you sure the chassis' are all 2001s and none are 1401s? I think they look identical, except for a few minor part substitutions. If two were a different model, I could imagine they'd be expecting a different yoke, and V-size would look weird.

DogP
 
DogP said:
From looking at the schematics, it seems like a weird failure mode for the LS86 to affect vertical size with an otherwise good picture, but I guess anything's possible. Are you sure the chassis' are all 2001s and none are 1401s? I think they look identical, except for a few minor part substitutions. If two were a different model, I could imagine they'd be expecting a different yoke, and V-size would look weird.

DogP
Click to expand...

Yea im not sure it's the chip, but since all the ones in my stash were bad I figured I'd try some new ones and go from there. It's been a while since I've done chassis/board work.

One thing i noticed was R802 is listed in the schematic as 1K…when I tested them they were 10K, so I swapped them with 1K resistors. Maybe a typo, so I'll try swapping it back and see if there is any difference.

They are all labeled KTN-2001 on the chassis, so I think I'm good there, but I should verify the yoke is good on this tube. I have a tube I necked so I have an extra yoke if anything.
 
Interesting enough…my working chassis are on tubes with a yoke of 2.1ohms on red/blue and 14ohms on green yellow..

This tube has 2.1 and 59. That might explain the wide image. I have another yoke I can swap.
 
@DogP spot on. Different tube with the correct 14ohm resistance on the yoke, adjustments work perfectly and no more vertical fold.

Still fighting the sync issue, but new chips are in the Mail. Fingers crossed.
 
Nice! Yeah, makes sense that the horizontal looked OK with a similar winding, but vertical was way off w/ a much different vertical winding.

DogP
 
one of the chassis is working now after putting new a new 74LS86.

Still have 1 that doesn't sync. So I'll have to keep working on that one. 3 out of 4 isn't bad! Now I have to yoke swap as well.

Thanks for the help :)
 

Attachments

  • 8E122124-A8DD-44B9-BBFF-A9D459F46A1C.jpeg
    8E122124-A8DD-44B9-BBFF-A9D459F46A1C.jpeg
    3.2 MB · Views: 6
DogP said:
Nice! Yeah, makes sense that the horizontal looked OK with a similar winding, but vertical was way off w/ a much different vertical winding.

DogP
Click to expand...
Check this out! I was about to swap the yoke with one from a broken tube, and I noticed the yoke winding looked different.

The "bad" yoke only had 1 wire from the winding going to each the green and yellow terminal. Then I saw it…someone twisted them together and taped it to the yoke. When I put each wire back to the green/yellow posts, resistance is now correct!

Never seen that hack before haha
 

Attachments

  • CBBE066D-0C84-454F-90E3-C2F6AA7C42BC.jpeg
    CBBE066D-0C84-454F-90E3-C2F6AA7C42BC.jpeg
    1.7 MB · Views: 9
I'm having some issues with my KT-3414DF. I seem to have partial, but not complete, horizontal collapse (see image). Do I follow the standard procedure for fixing this or is there something else wrong? This is the "standard procedure" that I'm referring to:
  • Replace HOT (Q712)
  • Replace T303
  • Replace L304
I've had this happen before, and I was able to fix it by adjusting the horizontal width in the OSD, but I've maxed it out, and it's still not wide enough.

It seems like CasinoTech no longer carries these parts. How can I go about acquiring these parts?
 

Attachments

  • KT-3414_Horizontal_Width.jpg
    KT-3414_Horizontal_Width.jpg
    2.8 MB · Views: 5
i just notice my mistake on the first post#
I posted wrong location
on the linearity Coil L304
i was looking at the TS chart
I got that location from in the manual 5-2-6 H-Linearity failure


Anyway Its the L701 7R5 printed on the part
replace Q710, Check Value R732 & R733
For H- Linearity drive.
Its best to just replace Q710 if its soldered in good.
These heatsink don't give just the transistor connection
confirm its soldered in good first!



So you swapped the parts from a working chassis?
 
I'm looking for a cap list for KT-3414df. Does the list in post #1 apply to KT-3414df as well?
 
You must log in or register to reply here.

Similar threads

mecha
how I service K4900s (caps/soldering/helpful tips)
Replies
4
Views
183
mecha
mecha
jjhudgins
Kortek KTN-2001N Cap kit question
Replies
2
Views
261
CharlieG
CharlieG
Phetishboy
13” Kortek Green/ Color Issues
Replies
6
Views
260
WadeLanham
WadeLanham
paul400
K4915 cap
Replies
5
Views
246
paul400
paul400
z0ner
Bad Caps and their Symptoms for Common Monitors
Replies
1
Views
339
R64
R64
Back
Top Bottom